Andy Murray's fiancee Kim Sears wore a Parental Advisory: Explicit Content sweatshirt during the Australian Open final. For 30 years this logo and its predecessors have been more than a little hijacked, writes Gareth Rubin.

The logo is now famous from thousands of albums from hip hop, heavy metal and other more iconoclastic musical genres.

The seeds were sown for it in 1985 by the Parents Music Resource Center, co-founded by Tipper Gore, wife of later Vice President Al Gore. Then it was "Explicit Lyrics: Parental Advisory". It has been slightly rejigged a couple of times and the current version - with its stark black and white lettering - is from 1993. It made its way to Britain in the 1990s. But Sears's tongue-in-cheek clothing is indicative of the way the label has become a mark of rebellion.

"It's become a real badge of honour to have that sticker on your CD now," says Dan Stubbs, news editor of music weekly NME. "It came out of this puritanical drive in America against rock and gangsta rap but completely backfired because bands would add in extra swearing just to get the sticker. Kids would want to buy that album because it had the label on and it made your CD seem cool. After all, isn't music partly about annoying your parents?"

In the UK, the scheme is co-ordinated by the music industry body, the BPI, which says that explicit content includes "strong language", "references to violence or sexualised behaviour", "racist, homophobic, misogynistic or other language" or "dangerous or criminal behaviour which could glamorise it".

But Gennaro Castaldo from the BPI admits that the label can undermine its own purpose. "Yes, there is that badge of honour aspect to it," he says. "The impulse behind it is to make parents and consumers aware of the content but it does have a dual effect - after all we've all been teenagers driven by a need to be anti-establishment and anti-parents. That's not going to change."